David Veldt noticed something strange about the people that LinkedIn was suggesting he knew. Apart from connections with mutual friends and colleagues, it started suggesting people he had no connection to that LinkedIn should know about. For example, it suggested someone whom he had emailed with a few times once, and someone he followed on Twitter (he hadn't connected his Twitter account to LinkedIn).

It also suggested someone with the same name as his high school girlfriend. He was friends with the ex on Facebook, but LinkedIn told him that it never uses one's Facebook data.

Go to an attractive young woman's page, and note that very often all the people recently viewed by people who viewed her page are other attractive women. Basically, there are guys out there using LinkedIn to trawl around for hot babes. Gross.

4.The creepy faux-personal email notifications.

Instead of saying it's a notification from LinkedIn, a friend request appears as a message from the name of the sender. It's almost like the tricky and cloying email subject lines the Obama campaign famously used. Frustratingly, they definitely work — I end up clicking on these notices because for a split second, I think they're from a person I know.

This winter, LinkedIn sent out email alerts to the top 20% of users telling them how special they were, and encouraged them to share the news. The thing is, since LinkedIn has about 100 million users, this means 20 million people (approximately the population of New York state) were the "special" ones. If you also take into account how many of those 100 million users are the kind of people who set up an account out of a vague sense of professional obligation but only log in occassionally while job seeking, the pool gets smaller, and those top 20% fish get bigger.

In June 2012, LinkedIn had a security breach, and many passwords were leaked; a site was set up where you could find out if yours was one of them. BuzzFeed FWD tested out various depressing passwords. (Yes, someone had "password," and yes, it was leaked.)

LinkedIn currently has no "block" feature, which makes it the one major social media platform where a stalker or harasser can keep contacting a victim. Because LinkedIn is important for people who are job seeking, deleting profiles is not a very good solution. BuzzFeed recently looked in depth at the stalker problem on LinkedIn.

There are privacy settings where you can adjust your networks or go completely private, but they don't address a situation where a current or former coworker is harassing you and you want to keep your network open to actively job search.

9.It knows how many shared contacts you have with people WHO AREN'T EVEN ON LINKEDIN.

These are people who haven't even joined the service, yet LinkedIn knows how many shared contacts you have. Presumably, this means they know how many of your current contacts also have this person in their email address book.

Basically, even if you haven't signed up for the service, LinkedIn is keeping a dossier on you.

10.Your lurking isn't safe. Here's how to find out who lurked you and then turn yourself anonymous:

LinkedIn lets you see who looked at your page, but only if you agree to make your own viewing public too. Lucky for us creeps, you can turn public viewing on just long enough to see who looked at you, then turn it off.

On the home page, click "See who's viewed your profile!" on the right-hand side.

LinkedIn has set you by default to "semi-anonymous," which means you can't see the names of the people who looked at you, but they can see just where you worked.

In order to see who viewed you, temporarily change your account to the full view option.